[R-390] TV-7/U (Square peg, round hole)

[Flowertime01 at wmconnect.com]

Bob,

If you are going to do a lot of these tubes you may want to build an adapter.

Octal base relays with plastic covers make nice adapters.

You open the relay top and unsolder the relay wires from the octal socket 
pins.
You solder pig tail wires to your new socket and mount it in the top plastic 
cover of the relay case.

Feed the pig tail wires into the octal socket base pins.
Replace the cover screws between the base and cover of the relay.

Pull the pig tail wires out of the octal pins to look nice.
Solder the pig tail wires in the octal socket pins and trim.

Bob Camp wrote a good procedure to adopt any tube to any tube tester.
Many tubes were missed in many tube tester lists.

Watch the TV7 knobs as you set it up for a known tube. 
You see that a couple switches set the filament pins.
One sets the cathode one sets the plate.
And so on down the line of switch settings.

The same knob has the same function on every tube.

Some other tube testers are pin to function dependent.
The switch serves the same pin every time and selects, fil, cath, plate, open.

The bias selects a grid bias.

There are other setup I do not remember off the top of my head
Do a bit of study and your tube tester becomes a lot more useful.

Adapters can be made, switch setting divined, bias values fathomed and meter 
values established.

Tube testers are just another item of test equipment and new ways to apply 
them can be discovered all the time. Some think tube testers just make good foot 
rest, poor door stops or paper weights. Others find all kinds of ways to 
apply the test instrument in creative ways and gain meaningful test results from 
the experiment of the moment.

Roger AI4NI   </HTML>